Ports of Auckland Seeks to Deepen Shipping Channel for Growth

Like many ports around the world, Auckland, New Zealand is finding itself challenged to deal with the increasing size of modern vessels.

Ports of Auckland recently applied to the Auckland Council for consent to deepen the city's shipping channel. The proposal will be coming up for a consent hearing and work on deepening the channel could start in 2021.

Currently, the largest container ships calling in Auckland now carry up to 5,000 TEUs, but the shipping lines want to bring 6-7,000 TEU ships into the port within the next two to three years. Longer term, the port authority is also anticipating handling newer classes of Panamax ships that can carry around 12,000 TEU.

The channel is currently 12.5 meters deep at low tide, but new Panamax ships, which are up to 366 meters in length, require a maximum draft of 15.2 meters. Ports of Auckland is applying to deepen the channel to approximately 14 meters explaining that it will use a technique known as tidal windows to accommodate the largest ships. Largest ships would enter and exit the port during period of high tide which provide sufficient the draft of those vessels. In its announcement, the port said this approach would be the most efficient way to accommodate larger container ships as it would be able to minimize dredging and the reduce cost of the project.

To create a tidal window suitable for new Panamax ships to access port safely, the channel leading into Auckland we will need a channel which is 14 meters deep on the straights and 14.2 meters deep on the bends. The berth, however, will need to be dredged to 15.5 meters so that ships remain afloat through a full tide cycle.

The dredging will be done by a digger on a barge as that would be the lowest impact method available. The digger will have a long arm to reach down to the seabed to scoop out material. The channel bed is mostly soft material like marine muds, mudstones and some sandstone and gritstone, which can be easily removed. No blasting is required.

In making the application for the dredging project, the port authority explained that Auckland's population is forecast to grow significantly, with a million more people expected to live in the area by 2050. To handle this growth the port said I is necessary to undertake this project to maintain the needed flow of international goods.